// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IPC_IPC_CHANNEL_MOJO_H_
#define IPC_IPC_CHANNEL_MOJO_H_

#include <stdint.h>

#include <vector>

#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/scoped_vector.h"
#include "base/memory/weak_ptr.h"
#include "base/synchronization/lock.h"
#include "build/build_config.h"
#include "ipc/ipc_channel.h"
#include "ipc/ipc_channel_factory.h"
#include "ipc/ipc_export.h"
#include "ipc/mojo/ipc_message_pipe_reader.h"
#include "ipc/mojo/ipc_mojo_bootstrap.h"
#include "ipc/mojo/scoped_ipc_support.h"
#include "mojo/public/cpp/system/core.h"

namespace IPC {

// Mojo-based IPC::Channel implementation over a platform handle.
//
// ChannelMojo builds Mojo MessagePipe using underlying pipe given by
// "bootstrap" IPC::Channel which creates and owns platform pipe like
// named socket. The bootstrap Channel is used only for establishing
// the underlying connection. ChannelMojo takes its handle over once
// the it is made and puts MessagePipe on it.
//
// ChannelMojo has a couple of MessagePipes:
//
// * The first MessagePipe, which is built on top of bootstrap handle,
//   is the "control" pipe. It is used to communicate out-of-band
//   control messages that aren't visible from IPC::Listener.
//
// * The second MessagePipe, which is created by the server channel
//   and sent to client Channel over the control pipe, is used
//   to send IPC::Messages as an IPC::Sender.
//
// TODO(morrita): Extract handle creation part of IPC::Channel into
//                separate class to clarify what ChannelMojo relies
//                on.
// TODO(morrita): Add APIs to create extra MessagePipes to let
//                Mojo-based objects talk over this Channel.
//
class IPC_MOJO_EXPORT ChannelMojo
    : public Channel,
      public MojoBootstrap::Delegate,
      public NON_EXPORTED_BASE(internal::MessagePipeReader::Delegate) {
public:
    // True if ChannelMojo should be used regardless of the flag.
    static bool ShouldBeUsed();

    // Create ChannelMojo. A bootstrap channel is created as well.
    static scoped_ptr<ChannelMojo> Create(
        scoped_refptr<base::TaskRunner> io_runner,
        const ChannelHandle& channel_handle,
        Mode mode,
        Listener* listener);

    // Create a factory object for ChannelMojo.
    // The factory is used to create Mojo-based ChannelProxy family.
    // |host| must not be null.
    static scoped_ptr<ChannelFactory> CreateServerFactory(
        scoped_refptr<base::TaskRunner> io_runner,
        const ChannelHandle& channel_handle);

    static scoped_ptr<ChannelFactory> CreateClientFactory(
        scoped_refptr<base::TaskRunner> io_runner,
        const ChannelHandle& channel_handle);

    ~ChannelMojo() override;

    // Channel implementation
    bool Connect() override;
    void Close() override;
    bool Send(Message* message) override;
    bool IsSendThreadSafe() const override;
    base::ProcessId GetPeerPID() const override;
    base::ProcessId GetSelfPID() const override;

#if defined(OS_POSIX) && !defined(OS_NACL)
    int GetClientFileDescriptor() const override;
    base::ScopedFD TakeClientFileDescriptor() override;
#endif // defined(OS_POSIX) && !defined(OS_NACL)

    // These access protected API of IPC::Message, which has ChannelMojo
    // as a friend class.
    static MojoResult WriteToMessageAttachmentSet(
        const std::vector<MojoHandle>& handle_buffer,
        Message* message);
    static MojoResult ReadFromMessageAttachmentSet(
        Message* message,
        std::vector<MojoHandle>* handles);

    // MojoBootstrapDelegate implementation
    void OnBootstrapError() override;

    // MessagePipeReader::Delegate
    void OnMessageReceived(Message& message) override;
    void OnPipeClosed(internal::MessagePipeReader* reader) override;
    void OnPipeError(internal::MessagePipeReader* reader) override;

protected:
    ChannelMojo(scoped_refptr<base::TaskRunner> io_runner,
        const ChannelHandle& channel_handle,
        Mode mode,
        Listener* listener);

    void InitMessageReader(mojo::ScopedMessagePipeHandle pipe, int32_t peer_pid);

    Listener* listener() const { return listener_; }
    void set_peer_pid(base::ProcessId pid) { peer_pid_ = pid; }

private:
    // ChannelMojo needs to kill its MessagePipeReader in delayed manner
    // because the channel wants to kill these readers during the
    // notifications invoked by them.
    typedef internal::MessagePipeReader::DelayedDeleter ReaderDeleter;

    void InitOnIOThread();

    scoped_ptr<MojoBootstrap> bootstrap_;
    Listener* listener_;
    base::ProcessId peer_pid_;
    scoped_refptr<base::TaskRunner> io_runner_;

    // Guards |message_reader_|, |waiting_connect_| and |pending_messages_|
    //
    // * The contents of |pending_messages_| can be modified from any thread.
    // * |message_reader_| is modified only from the IO thread,
    //   but they can be referenced from other threads.
    base::Lock lock_;
    scoped_ptr<internal::MessagePipeReader, ReaderDeleter> message_reader_;
    ScopedVector<Message> pending_messages_;
    bool waiting_connect_;

    scoped_ptr<ScopedIPCSupport> ipc_support_;

    base::WeakPtrFactory<ChannelMojo> weak_factory_;

    DISALLOW_COPY_AND_ASSIGN(ChannelMojo);
};

} // namespace IPC

#endif // IPC_IPC_CHANNEL_MOJO_H_
